Spinal locomotor circuits can be accessed and trained in humans with appropriate stimuli and practice. Treadmill training and FES-cycling protocols are being increasingly utilized for persons with CMS injuries to exploit this potential in an effort to improve coordination and, if possible, to restore or promote ambulation. Activation of spinal circuits may also drive cortical reorganization and further augment motor recovery. Cerebral palsy (CP), the most prevalent physical disability originating in childhood, is characterized by abnormal motor control as a result of a static brain lesion in a developing nervous system. A consequence of the resultant inappropriate descending input is that spinal mechanisms that promote coordinated reciprocal movements in the lower extremities are often underutilized and therefore may develop abnormally. This has a direct negative effect on motor development and initiates a cascade whereby restricted amounts and types of movements limit the reinforcement or development of motor pathways in the nervous system, further reducing motor potential. Our specific aim in this initial investigation is to conduct a three month motor-assisted (passive) cycling program using a special computerized motor-driven cycle in 20 ambulatory and non-ambulatory children with CP with the primary goal to train spinal locomotor circuits and thereby improve motor coordination and function. Secondary goals are to modulate spasticity and muscle stiffness, and enhance cortical plasticity. Cycling is a form of locomotion shown to have similar timing and phasing to walking and evidence of shared neural circuitry, and could provide a more effective and feasible in-home alternative to therapist-assisted supported treadmill training regimens. Fast (50RPM) motor-driven cycling produces reciprocal muscle activation in normals that may be even greater in persons with spasiticy. If it is found that cycling stimulates neural and motor recovery in CP, the data obtained in this prospective observational study will be used to support a RCT of passive and perhaps active-assisted cycling in CP. [unreadable] [unreadable]